• Korean Journal of Materials Research
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• v.28 no.2
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• pp.118-123
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• 2018

5 nm-thick $SiO_2$ layers formed by plasma-enhanced chemical vapor deposition (PECVD) are densified to improve the electrical and interface properties by using nitric acid oxidation of Si (NAOS) method at a low temperature of $121^{\circ}C$. The physical and electrical properties are clearly investigated according to NAOS times and post-metallization annealing (PMA) at $250^{\circ}C$ for 10 min in 5 vol% hydrogen atmosphere. The leakage current density is significantly decreased about three orders of magnitude from $3.110{\times}10^{-5}A/cm^2$ after NAOS 5 hours with PMA treatment, although the $SiO_2$ layers are not changed. These dramatically decreases of leakage current density are resulted from improvement of the interface properties. Concentration of suboxide species ($Si^{1+}$, $Si^{2+}$ and $Si^{3+}$) in $SiO_x$ transition layers as well as the interface state density ($D_{it}$) in $SiO_2/Si$ interface region are critically decreased about 1/3 and one order of magnitude, respectively. The decrease in leakage current density is attributed to improvement of interface properties though chemical method of NAOS with PMA treatment which can perform the oxidation and remove the OH species and dangling bond.

• Korean Journal of Materials Research
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• v.27 no.2
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• pp.113-118
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• 2017

Natural and expandable graphites were chemically treated in acidic aqueous solutions such as acetic acid or mixtures of acetic acid and nitric acid. Structures and thermal conductivities of the as-treated graphites were characterized in detail. Both graphites were significantly oxidized in the mixed acidic solution of $H_2SO_4$ and $HNO_3$, which condition was generally used for the oxidation of carbon nanotubes. This considerable oxidation of graphites caused a depression of their thermal conductivity. The structural characteristics, obtained by XRD and XPS, show that the graphites treated in the relatively weak acidic conditions (acetic acid or mixture of acetic acid and nitric acid) were quite similar to the untreated graphites. However, the thermal conductivities of both acidic-treated graphites were remarkably increased.

• Carbon letters
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• v.5 no.2
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• pp.55-61
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• 2004

Adsorption isotherms of p-nitrophenol from its aqueous solutions on two samples of activated carbon fibres and two samples of granulated activated carbons have been determined in the concentration range 40~800 mg/L (ppm). The surface of these carbons was modified by oxidation with nitric acid and oxygen gas, and by degassing the carbon surface under vacuum at temperatures of $400^{\circ}C$, $650^{\circ}C$ and $950^{\circ}C$. The oxidation of carbon enhances the amount of carbon-oxygen surface groups, while degassing decreases the amount of these surface groups. The adsorption of p-nitrophenol does not depend upon the surface area alone but appears to be influenced by the presence of oxygen groups on the carbon surface. The adsorption decreases on oxidation while the degassing of the carbon surface enhances the adsorption. The decrease in adsorption depends upon the strength of the oxidative treatment being much larger in case of the oxidation with nitric acid, while the decrease in adsorption on degassing depends upon the temperature of degassing. The results show that while the presence of acidic surface groups which are evolved as $CO_2$ on degassing suppress the adsorption of p-nitrophenol, the presence of non acidic surface groups which are evolved as CO on degassing tend to enhance the adsorption. Suitable mechanisms compatible with the results have been presented.

• Journal of the Semiconductor & Display Technology
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• v.13 no.3
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• pp.13-19
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• 2014

Phosphoric acid was used as etching agent instead of conventional peroxide - based chemicals for forming pattern of ultra definition display. Etchant was synthesized by mixing etching agent, oxidation agent, buffer solution, and additive into solvent, deionized water. Thicknesses of copper, main metal of ultra definition display, for etching, were 10,000 and $30,000{{\AA}}$. Etch stop of good low skew for proper pattern formation has been occurred at the content ratio of phosphoric acid 60 - 64%, nitric acid 4 - 5%, additive(potassium acetate) 1 - 3%. Buffer solution(acetic acid) decreased the metal contact angle $63.07^{\circ}$ to $42.49^{\circ}$ for benefiting pattern formation. Content variations on four components (phosphoric acid, nitric acid, acetic acid, potassium acetic acid) of the etchant with storage time were within 3 wt% after 24 hrs of etching work.

• Journal of Microbiology and Biotechnology
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• v.9 no.5
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• pp.650-654
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• 1999

Undaria pinnatifida oxidized by nitric acid had a high capacity of Cu/sup 2+/ uptake (3.5 mmol Cu/sup 2+/g dry mass) at pH 4 and showed high affinity to Cu/sup 2+/ and Pb/sup 2+/, in a mixed-metal system, compared to Ca/sup 2+/ and Mg/sup 2+/. The IR spectrum showed increase of carboxylic acid on the surface of Undaria pinnatifida, mostly due to the effect of the oxidation reaction.

• The Korea Journal of Herbology
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• v.23 no.2
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• pp.123-136
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• 2008

Objectives : To estimate the value of the Gyungokgo as therapeutic agent preventing against aging with an analysis of the ingredients and the bio-activating effects by enzymologic methods. Methods : A quantitative analysis of general ingredients' of the Gyungokgo's extract was done first. The effects on electronic donating ability, SOD-like activity, nitric oxide inhibition, xanthine oxidase inhibition, whitening effect have been investigated in the physiological activity measurement of function experiment. Results : The contained hydrolyzed amino acid is Valine, Aspartic acid, Arginine, Isoleucine and the contained free amino acid is Arginine, Phenylalanine, Valine, Glycine. The derivative of free amino acid is Phosphoserine, Carnocine, ${\gammer}$-Aminoisobutyric acid. And the Gyungokgo contains 14 species of minerals, K>Na>Ca>Mg>Fe>Al>Mn. Then, to assure of the Gyungokgo's anti-oxidation, these following subjects -polyphenol, electronic donating ability, SOD-like activity, nitric oxide inhibition, xanthine oxidase inhibition, tyrosinase inhibation- are analyzed and show high activity especially the most in chloroform extracts, (every ingredients written by the order of high amount) Conclusions : The Gyungokgo contains many materials functioning as anti-oxidation, neurotransmitter, anti-fatigue and immune agent.

• Journal of the Korean Electrochemical Society
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• v.2 no.2
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• pp.93-97
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• 1999

From the anodic peak currents of cyclic voltammograms for Ag(I)/Ag(II) couple obtained with the variation of nitric acid concentration, Ag(I) concentration and solution temperature at a Pt electrode in concentrated nitric acid solutions, the diffusion coefficients of Ag(I) ion were evaluated to estimate the limiting current density of Ag(II)-mediated electrochemical oxidation (MEO) process, which has been effectively used for the complete destruction of hazardous organic materials. The results showed that, due to the water decomposition reaction which occurred simultaneously with the Ag(I) ion oxidation, background subtractions for the cyclic voltammograms were required to estimate the correct peak currents. The empirical relationship for the diffusion coefficient of Ag(I) was suggested as a function of solution viscosity and temperature.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.10a
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• pp.342.1-342
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• 2002

• Carbon letters
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• v.9 no.1
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• pp.8-16
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• 2008

Oxidized activated carbons were prepared by reacting steam-activated carbon developed from pecan shells with nitric acid of varying strength (15, 30, 45 and 60%). The textural properties and the chemistry of the surface of the non-oxidized and of the oxidized carbons were determined from nitrogen adsorption and base neutralization capacities. The uptake of Pb(II) and Cd(II) from aqueous solution by these carbons was determined by kinetic and equilibrium experiments as well as by the column method. Treatment with nitric acid brought about drastic decrease in surface area and remarkable increase in the pore size of the carbon with these changes depending on the strength of nitric acid. Nitric acid increased the surface acidity by developing new surface oxygen functional groups of acidic nature. $HNO_3$-oxidized carbons exhibited high adsorption capacities for Pb(II) and Cd(II). The adsorption of these ions increased with the decrease of the surface pH of the carbon and with the increase of the solution pH from 2.5 to 6 and 7. The amount adsorbed from lead and cadmium was also related to the amount of surface acidity, the pH of the point of zero charge and on some metal ion parameters. Cadmium and lead uptake by the investigated carbons followed pseudo-second order model and the equilibrium sorption data fitted Langmuir adsorption model.

• Journal of Environmental Science International
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• v.21 no.1
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• pp.113-123
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• 2012

A unit emission reduction of nitrous oxide ($N_2O$) from anthropogenic sources is equivalent to a 310-unit $CO_2$ emission reduction because the $N_2O$ has the global warming potential (GWP) of 310. This greatly promoted very active development and commercialization of catalysts to control $N_2O$ emissions from large-scale stationary sources, representatively nitric acid production plants, and numerous catalytic systems have been proposed for the $N_2O$ reduction to date and here designated to Options A to C with respect to in-duct-application scenarios. Whether or not these Options are suitable for $N_2O$ emissions control in nitric acid industries is primarily determined by positions of them being operated in nitric acid plants, which is mainly due to the difference in gas temperatures, compositions and pressures. The Option A being installed in the $NH_3$ oxidation reactor requires catalysts that have very strong thermal stability and high selectivity, while the Option B technologies are operated between the $NO_2$ absorption column and the gas expander and catalysts with medium thermal stability, good water tolerance and strong hydrothermal stability are applicable for this option. Catalysts for the Option C, that is positioned after the gas expander thereby having the lowest gas temperatures and pressure, should possess high de$N_2O$ performance and excellent water tolerance under such conditions. Consequently, each de$N_2O$ technology has different opportunities in nitric acid production plants and the best solution needs to be chosen considering the process requirements.